Several examples of the photolysis of polymers with di, tri or other polyfunctional azide crosslinking agents are shown in the art. For example, Laridon et al., U.S. Pat. No. 3,467,518, described one formation of a resist image by the photochemical crosslinking of polymers carrying groups which are reactive with intermediates derived from the photochemical decomposition of a compound containing at least two azidosulfonyl groups. Such crosslinking is believed to occur because of the formation and subsequent reaction of a disulfonylnitrene intermediate which presumably serves as the crosslinking agent.
In view of such art, it would not be expected that any product resulting from the photolysis of a solvent soluble polymer and a mono-sulfonyl azide would be made solvent insoluble after photolysis. However, it has now been unexpectedly found that a mixture of a nitrogen containing polymer with a mono-sulfonyl azide will become solvent insoluble after exposure to a UV-containing light source. Moreover, such insolubilized areas quite unexpectedly develop a variety of colors which are extremely stable and which do not appreciably change with time if the photolysis is carried out on a cellulosic material.